Looking at other information, seems like the current "hard" rumours are:

1.4-2.2 faster and more consistent lens

28-140mm zoom

Hotshoe

Wifi

Swivel screen

Plus, i guess a host of ergonomic software improvements, will make this new beast a very tempting upgrade.

I may have to eat my words about being perfectly happy with the original RX100

If they pull all the above off, Sony will have have raised the bar already set by the RX100 to another level!

Who of us RX100 users would seriously be interested in upgrading based on the above? I would be pretty tempted, based on the faster lens for sure, longer reach would be cool too, and the Wifi. Maybe hotshoe for later.